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Full text of "Treatise On Applied Analytical Chemistry(Vol-1)"

no

SULPHUR

STANNOUS   CHLORIDE
SnCla + aHaO = 226

White or yellowish crystals, soluble in water, alterable in moist air.
It may contain, as impurities, oxychloride (insoluble), iron, etc. (see Stannic
Chloride), and may be adulterated with sodium chloride or sodium, mag-
nesium or zinc sulphate. These impurities are detected as in stannic, chloride
(tests i, 3, 7, 8 and 9). The presence- of oxychloride is indicated by the
incomplete solubility of the salt in water and in alcohol.

Its value depends essentially on the proportion of tin in the stannous
condition, dctenninable as follows :

Quantitative Determination (Goppel and Frankel's method).3-4

grams of the chloride ;ire dissolved in 30.....40 c.c. of 10% hydrochloric, acid

and the liquid diluted to 500 c.c., 50 c.c. of the solution being then treated,
in a bottle with a ground stopper, with 50 c.c. N/ro--K.,( T.,()7. After 15
minutes, 10......15 c.c. of potassium iodide solution and 5 10 c.c, of hydro-
chloric acid (both i : 10) arc added, and, after a further half an bonr, the
liquid is diluted with 200 c.c. of water and the iodine liberated titrated with
N/io-thiosiilphate and starch paste. The difference in c.c. between the.
volumes of dichromate and thiosnlphate, multiplied by 0-0113 gives the
amount of SuCL + i'II2(), and multiplied by 0*00595 the amount of tin
in the quantity of substance taken for titnilion.

StanncYus chlorides of <)<) 000% and of <)i>-8<).S<7% are now sold, the latter
being guaranteed to contain 51 -5.!% Su. Adulteration with zinc or magnesium
sulphate is now rare.

SULPHUR

Native or mine-mi sulphur, consisting of sulphur mixed with varying
proportions of gangue (chalk, gypsum, clay, bituminous matter), is the raw
material from which the bulk of the sulphur of commerce is derived. The
latter is divided into : (".rude- sulphur of rst, 2nd and 3rd qualities, in lemon-
yellow loaves, which are more or less shining, pale and opaque according to
the gra.de , Refined snlp/iur, in loaves, sticks or powder ((',round and sieved
sulphur), bright lemon-yellow and shining; Sublimed sulphur or Flowers
of sulphur, a line, light, yellowish powder. Further, Mugiste-r of sulphur
or precipitated sulphur (obtained by treating calcium sulphide solution with
hydrochloric acid), for pharmaceutical uses, forms a very fine, light, amor-
phous powder of dirty yellowish-white colour; finally, ('oppercd- sulphw',
for agricultural uses, is a mixture of winnowed sulphur with o"5"5% (usually
3-5%) f->f copper sulphate.

For certain purposes (manufacture of sulphuric acid), iron pyrites may
be regarded as a sulphur mineral and will be considered here, These
substances are examined as follows:ent, a little bromine water is added prior to the boiling. in 50 c.c. of water.